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Discussion Starter · #1 ·
Hi everybody

I wanted to know what is the relationship between air flow and PSI. For example the stock IC on an aero 9-5 flows 85 cubic feet per minute and turbo boost is 20 PSI, if we change the IC with an other, which flows 120 cubic feet per minute then the turbo don't need to boost so high, in order to give the requested from ECU air mass. How big would be the decrease of boost in PSI on the same conditions?

9-5 aero
 

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Originally posted by 9-5 aero:
[qb]I wanted to know what is the relationship between air flow and PSI. For example the stock IC on an aero 9-5 flows 85 cubic feet per minute and turbo boost is 20 PSI, if we change the IC with an other, which flows 120 cubic feet per minute then the turbo don't need to boost so high, in order to give the requested from ECU air mass. How big would be the decrease of boost in PSI on the same conditions? [/qb][/b]
The reduction in static pressure back towards the turbocharger will make the wastegate open more, which will reduce backpressure to the engine. A general rule of thumb is that for every PSI of static pressure-reduction on the compressor side you get 2-3 psi of reduction in static pressure on the exhaust side.

The exact reduction depends greatly on the engine itself and the type of ECU.

A better cooling intercooler will also have a similar effect as it lowers the pressure required to attain a given air-mass/combust by making the air more dense.

Also, when you say "turbo boost is 20 psi", is this static or dynamic boost pressure ... and is it in the mid-range, or towards redline? This information effects the result greatly ...

Adrian W~
 

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Discussion Starter · #3 ·
Hi

I mean 20 PSI max boost let's say @ 3000rpm and then it drops to 15 PSI at redline for example

9-5 aero
 

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Originally posted by 9-5 aero:
[qb]I mean 20 PSI max boost let's say @ 3000rpm and then it drops to 15 PSI  at redline for example.[/qb][/b]
Well, since the the pressure is measured after the intercooler's restriction, only the reduction in exhaust backpressure, and subsequent increase in flow efficiency through the engine, will lower the boostpressure/air-mass ratio.

Now if we assume the IC's cool the same, and the increase in flow efficiency through the engine is roughly 5%, then the drop in boost pressure for a given air-mass/combust is from 15 psi --> 13.5 psi ... all other things equal.


Maybe in reality on some engines the airflow efficiency will increase more, or increase less, than 5% ... but for the sake of approximation there it is.

Adrian W~
 

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Discussion Starter · #5 ·
I have ordered the IC from Abbott and on their site there is this info:

40% better air flow than standard
12% better cooling than standard

9-5 aero
 

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Originally posted by 9-5 aero:
[qb]40% better air flow than standard
12% better cooling than standard.[/qb][/b]
40% better flow through the intercooler unfortunately doesn't translate to 40% better flow-efficiency through the engine.

Now, if we combine the "estimation" of 5% flow efficiency through the engine with the 12% additional cooling you get about 12.8 psi for the same air-mass/combust.

Again, these are based off an unknown approximation. I think it should be very close, but unfortunately there is no exact way to predict the reduction in exhaust backpressure from a change in wastegate duty cycle without some direct measurement and/or calibration.

Adrian W~
 

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Discussion Starter · #8 ·
Originally posted by Adrian W:
[qb][/b]
40% better flow through the intercooler unfortunately doesn't translate to 40% better flow-efficiency through the engine.

Now, if we combine the "estimation" of 5% flow efficiency through the engine with the 12% additional cooling you get about 12.8 psi for the same air-mass/combust.

Again, these are based off an unknown approximation. I think it should be very close, but unfortunately there is no exact way to predict the reduction in exhaust backpressure from a change in wastegate duty cycle without some direct measurement and/or calibration.
[/qb]


Ok Adrian thanks. I will dyno the car again as soon as i have the IC installed and monitor boost and intake temps during the run.

9-5 aero
 

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Originally posted by Trionic:
[qb]It will give anyway a lot of boost adaption problems.... [/qb][/b]
On stock software, absolutely. But doesn't most modified-software have a broader adaption map?

If he's running 20 psi, his software shouldn't be stock.

Adrian W~

p.s. Make sure to take a datalogger to the dyno-session to log the temps and pressure! This would be a good experiment to approximate the flow-losses from the stock restrictive intercooler.
 

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There is no tuner worldwide able to calibrate a PWM map on a Trionic SW, sorry. Moreover, he's using a Maptun SW with Abbott IC... how should Maptun have a correct mapping for it?
If the boost adaption will not go down a lot, it will be just by chance....(or the IC is ****)
 

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Discussion Starter · #11 ·
Originally posted by Trionic:
[qb]There is no tuner worldwide able to calibrate a PWM map on a Trionic SW, sorry. Moreover, he's using a Maptun SW with Abbott IC... how should Maptun have a correct mapping for it?
If the boost adaption will not go down a lot, it will be just by chance....(or the IC is ****) [/qb][/b]
Trionic, do you have personal experiences of what you are saying or have you read it or see it somewhere? I know for example, that Philip HS had with Maptun stg 3 252 PS and with the the same SW after an uprated IC and Gas Flowed Head 269 PS.

http://www.viggenfactfile.de/dynolog.html

In addition not all the cars react the same and i know, that my ECU is for an uprated IC rogrammed. I don't think, that the IC from Maptun is much different fom Abbotts' one and i have also this info from Abbott:

"At the moment the standard ECU flows 85 cubic feet per minute of air. Ours flows 125 cubic feet per minute of air, thus reducing temperatures and back pressure and therefore, increasing the bhp between 15 and 20bhp. The ECU will self adapt to the high flow intercooler and will not need reprogramming".

Anyway, i will dyno the car after that and then we can be sure if it has adapted down or up. After this procedure has taken place we can talk again about that.
 

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Originally posted by 9-5 aero:
[qb] i have also this info from Abbott:

"At  the moment the standard ECU flows 85 cubic feet per minute of air.  Ours flows 125 cubic feet per minute of air, thus reducing temperatures and back pressure and therefore, increasing the bhp between 15 and 20bhp. The ECU will self adapt to the high flow intercooler and will not need reprogramming".

[/qb][/b]
Surely that should read:-
At the moment the standard intercooler flows 85 cubic feet per minute of air.

The last sentance is interesting as well...
 

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Originally posted by 9-5 aero:
[qb]Trionic, do you have personal experiences of what you are saying ... [/qb][/b]
He has looooots of it ...

If you instal the intercooler anyway, consider getting a slower-spooling 06 cm housing of a 9000 Aero's turbocharger. If you don't wish to take the risk of wasting your time, I'll be testing this out myself as soon as I can find the correct housing, and I will post resulting data-logs. (Hard to find in Southern California. Not many 9000 Aero's.)

Adrian W~
 

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Discussion Starter · #14 ·
Originally posted by aeropilot:
[qb][/qb][/b]
Surely that should read:-
At the moment the standard intercooler flows 85 cubic feet per minute of air

The last sentence is interesting as well


Yes it's an error. "Intercooler" instead of "ECU". Why is the last sentence interesting for you?

9-5 aero
 

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Because it says that the ECU will selfadapt to the IC I think that this statement should be seen in the light of Abbott lacking knowledge of custom tuning an ECU.

Normally, if you add a better IC to a T7 car, it will lean out. However, if the software is designed to give more fuel (or if you raise the fuel pressure), this can be avoided. BUT more fuel will reduce power. Let´s wait and see ...

Yours,

Philip
 

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Discussion Starter · #16 ·
Philip i think you have done the same on your Viggen before the Hirsch custom ECU. With stg 3 ECU, which wasn't programmed for the uprated IC and Gas flowed head you managed to get about 17 PS more (252 to 269). Was your car running lean at that time?

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Hi 9-5 Aero,

no, you are wrong. After I had my new engine done and the Hirsch Software made, I went to our local dyno shop to verify the results again - I´m a very sceptical mind, you know - they were spot on: 280 hp promised, 280 hp measured, on a dyno which is calibrated to an engine dyno.

I also wanted to give MapTun another chance, so I installed the MapTun ECU did a short adaptation run, and after cool-down, I dynoed the car with the MapTun ECU under exactly the same conditions than the Hirsch ECU, but it scored still far from the promised 285. However, compared to the dyno run before the installation of the big IC (and the gas flowing of the head), it gained quite some power. You can read about all this on my homepage.
A/F was not measured on this run.

But Vigge dynoed his car before and after IC install with MapTun SW, and his car leaned out, so he had the SW adjusted.

Yours,

Philip
 

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Originally posted by philip hs:
[qb]But Vigge dynoed his car before and after IC install with MapTun SW, and his car leaned out, so he had the SW adjusted.[/qb][/b]
Vigge's car maaaay have a slightly mis-calibrated MAF sensor. It's PWM signal is out of line with the standard calibration and OBDII readouts.

It may also be the fault of the OBDII reader, but I just thought it should be mentioned.

Air-filters are notorious for causing MAF sensors to read differently as they can change the flow shape and sometimes coat the PTC resistor in a fine film of oil.

Phillip, did you see your car lean out with the IC and ported head on stock software and stock airfilter? Mind you, the stock software runs about 13:1 in the mid-range around 3,000 RPM completely stock ... and about 11:1 at 5,500. Also, if it was leaner than this, was it transitory, or sustained? Just curious.

Adrian W~
 

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Originally posted by Adrian W:
[qb]Vigge's car maaaay have a slightly mis-calibrated MAF sensor.  It's PWM signal is out of line with the standard calibration and OBDII readouts.

It may also be the fault of the OBDII reader, but I just thought it should be mentioned.

Air-filters are notorious for causing MAF sensors to read differently as they can change the flow shape and sometimes coat the PTC resistor in a fine film of oil.
[/qb][/b]
I think Vigge should answer that.

Originally posted by Adrian W:
[qb]Phillip, did you see your car lean out with the IC and ported head on stock software and stock airfilter?[/qb][/b]
No, because I dumped the stock airfilter in early 2003. It was about the first mod I did to the Viggen. MAF and car still going strong... but I have cleaned the MAF in September 2003

Yours,

Philip
 

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Originally posted by Adrian W:
[qb]Vigge's car maaaay have a slightly mis-calibrated MAF sensor.  It's PWM signal is out of line with the standard calibration and OBDII readouts.

It may also be the fault of the OBDII reader, but I just thought it should be mentioned.

Air-filters are notorious for causing MAF sensors to read differently as they can change the flow shape and sometimes coat the PTC resistor in a fine film of oil.

[/qb][/b]
My car may have alot of issue, you know but it performs somw what deacant... We all know that there is now hell that a person who has newer tested your cars custom IC could fix you a T7 SW that would work perfect.
After my first dyno run with the IC the fuel maps needed some work (leaned out bad) and now they look some what OK.
The SW is far from perfect, but I dont have my hopes to high before I get the car in for custom mapping.
My engine load read from OBD falls short from 100% by some margin, which to my knowlegde is an fairly good idicator how well the SW fits to the big picture.

Once again do not mix HW parts from tuner to tuner, because they are not alike and all you will do is get your self into a mess sooner or later. Yes, you might save 100£ now, but if more work is needed you will spend that time for testing and adjustments.

Ps. Please dont say "my car wors just fine with custom HW parts and a bulk SW" if you have not tested it out completely...
 
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